Modular Approach to Tricyclic Heterocycles through Copper Catalysis and Functionalization by Palladium‐Catalyzed C–H Arylation

Abstract

A copper‐catalyzed Ullman reaction accompanied with oxidative C–N bond formation was used to access tricyclic heterocycles in a one‐pot operation by using atmospheric air as the terminal oxidant. This modular synthesis approach was used to synthesize previously known and novel azole‐containing heterocycles with different nitrogen position isomers. Fused heterocycles were further functionalized by palladium‐catalyzed direct C–H arylation methodology. Various electron‐rich and electron‐poor functional groups were tolerated in the ortho, meta, and para positions of the aryl bromides.